The aim is to systematically assess the health impact of a low-inflammatory diet intervention (full-diet or supplement), compared to usual diet or other dietary interventions, on weight change, inflammatory biomarkers, joint symptoms, and quality of life in adults with osteoarthritis, rheumatoid arthritis or seronegative arthropathy (psoriatic, reactive, ankylosing spondylitis or IBD-related), on outcomes assessed in prospective studies within 6 months of intervention commencement (PROSPERO CRD42019136567). Search of multiple electronic library databases from inception to July 2019, supplemented by grey literature searches, for randomised and prospective trials assessing the above objective. After exclusion of 446 ineligible studies, five randomised and two prospective trials involving 468 participants with either osteoarthritis or rheumatoid arthritis were included. GRADE assessment for all outcomes was very low. Meta-analyses produced the following standardised mean differences (SMD) and 95 % confidence interval (CI) 2–4 months following commencement of the diets favouring the low-inflammatory diet: weight SMD −0⋅45 (CI −0⋅71, −0⋅18); inflammatory biomarkers SMD −2⋅33 (CI −3⋅82, −0⋅84). No significant effects were found for physical function (SMD −0⋅62; CI −1⋅39, 0⋅14), general health (SMD 0⋅89; CI −0⋅39, 2⋅16) and joint pain (SMD −0⋅98; CI −2⋅90, 0⋅93). In most studies, the quality of dietary intervention (dietitian input, use of validated dietary compliance tool) could not be gauged. In conclusion, very low-level evidence suggests that low-inflammatory diets or supplements compared to usual diets are associated with greater weight loss and improvement in inflammatory biomarkers. More high-quality trials are needed to assess the health effects of a low-inflammatory diet more comprehensively and conclusively in arthritic conditions.

AimTo explore perceived barriers and enablers to weight management among people with obesity awaiting total knee or hip arthroplasty.DesignA nested qualitative study within a multi‐centre, quasi‐experimental pilot study comparing usual care weight management to a dietitian‐led weight‐loss diet.MethodsSemi‐structured individual interviews were conducted with adults with end‐stage osteoarthritis and a body mass index ≥30 kg/m2 waitlisted for primary total knee or hip arthroplasty. Participants with diverse sociodemographic characteristics and varied success with weight management in the pilot study were purposively sampled. Interviews were analysed using inductive thematic analysis, underpinned by constructivist–interpretivist epistemology. The Patient Activation Measure and Health Literacy Questionnaire were used for context when interpreting the findings.ResultsTwenty‐five participant interviews were conducted with a sociodemographically varied sample (aged 44–80 years, 9 born in Australia, 6 in paid employment and 11 lost ≥5% of their baseline weight). Four identified themes underpinned successful weight management: beliefs, adaptability, navigating healthcare and sociocultural context. Beliefs about whether weight was perceived as a problem, the expectation of weight loss and treatment‐related beliefs influenced participants' perspectives towards weight loss. Adaptability, the ability to overcome barriers to weight loss, comprised three subthemes; readiness to act, degree of independence and problem‐solving skills. Approaches towards navigating healthcare influenced uptake and adherence to weight management recommendations. Importantly, these themes were dependent on social and environmental circumstances, which influenced the type of barriers experienced and resources available to the individual.ConclusionDifferences in a person's beliefs, their ability to adapt and navigate healthcare and sociocultural context appear to explain successful weight management among people with end‐stage arthritis.Implications for the profession and/or patient careClinicians should allow for individualisation cognisant of the identified themes when providing advice and treatment to promote adherence to weight management interventions.ImpactThis study explored perceived barriers and enablers to weight management among people with obesity awaiting total knee or hip arthroplasty. Four identified themes underpinned successful weight management: beliefs, adaptability, navigating healthcare and sociocultural context. Beliefs about whether weight was perceived as a problem, the expectation of weight loss and treatment‐related beliefs influenced participants' perspectives towards weight loss. Understanding and assessing the contribution of each factor may guide weight management from clinicians treating patients with obesity and osteoarthritis.Reporting MethodThe data are reported using the COREQ guidelines.Patient or Public ContributionPatients contributed to the data collected.